Auto defrost refrigerator



April 23, 1968 R. E, KING 3,379,029

AUTO DEFROST REFRIGERATOR Filed April 29, 1966 INVENTOR.

RALPH E. K\NC-a ms TTORNEY United States Patent ()fice 3,379,029 Patented Apr. 23, 1968 3,379,029 AUTO DEFRGST REFRIGERATQR Ralph E. King, Louisville, Ky assignor to General Electric Company, a corporation of New York Filed Apr. 29, 1966, Ser. No. 546,264 4 Claims. (Cl. 62-18% ABSTRACT OF THE DESCLOSURE A household refrigerator comprising a cabinet divided by a horizontally insulated partition into an upper freezer compartment and a lower fresh food compartment. An evaporator chamber is positioned at the rear of the freezer compartment and has a single air outlet into the freezer compartment. Air from the freezer compartment is circulated (1) back to the evaporator chamber, and (2) to the fresh food compartment via a passageway at the front of the partition and back to the evaporator chamber by way of another passageway at the rear of the partition. A temperature sensing element, for controlling the condensing unit, is positioned in the fresh food compartment.

The present invention relates to household refrigerators and is particularly concerned with an auto defrost, single evaporator two compartment refrigerator.

Combination refrigerators including a single evaporator and a single fan for circulating air from the freezer and fresh food compartments over the evaporator are well knuown. One of the principal advantages of such refrigerators is the fact that the evaporator can be positioned outside or separate from both the refrigerated compartments where it can be periodically defrosted without substantially affecting the temperatures of the two compartments. Heretofore these refrigerators have included separate or substantially separate air circulating systems for respectively supplying refrigerated air to the freezer and to the fresh food compartments.

A primary object of the present invention is to provide a low cost auto defrost combination refrigerator of the above type particularly characterized by a simplified air flow system for maintaining the freezer and fresh food compartments at the desired operating temperatures.

Further objects and advantages of the invention will become apparent as the following description proceeds and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In accordance with the illustrated embodiment of the present invention there is provided a combination refrigerator comprising a cabinet divided by a horizontal insulating partition into an upper freezer compartment and a lower fresh food compartment. An evaporator chamber is positioned rearwardly of the freezer compartment and above the fresh food compartment and is separated from the freezer compartment by a vertical partition. A single evaporator is contained in the evaporator chamber. This chamber is provided with a single air outlet in the upper portion of the vertical partition communicating with the freezer compartment, a first air inlet in the lower portion of the partition for returning air to the chamber from the freezer compartment and a second inlet in the rear edge portion of the horizontal partition connecting the fresh food compartment with the evaporator chamber. All of the air cooled by the evaporator is discharged through the chamber outlet into the freezer compartment and most of this air, after circulating through the freezer compartment, is returned to the evaporator chamber through the first inlet. A portion of the air from the freezer compartment is conducted to the fresh food compartment through a passageway in and adjacent the front edge portion of the horizontal partition. The refrigerator also includes condensing means for supplying condensed refrigerant to the evaporator and control means for controlling the operation of the condensing means and the fan including a temperature sensing element positioned in the fresh food compartment.

For a more detailed description of the invention reference may be had to the accompanying drawing in which:

FIGURE 1 is a front elevational view, partly in section of a refrigerator cabinet including the present invention;

FIGURE 2 is a sectional view of a portion of the refrigerator of FIGURE 1 taken along line 22 of FIGURE 1; and

FIGURE 3 is a sectional view taken along line 33 of FIGURE 1.

With reference to the drawing, there is shown a refrigerator comprising insulated walls defining an upper freezer compartment I intended to operate at a temperature below freezing and a lower fresh food compartment 2 intended to operate at above freezing temperatures of about 3540 F. The two compartments are separated by a horizontal insulating partition 3. The access opening to the freezer compartment is closed by a small inner door 4- while the access opening to the entire interior of the cabinet including both the freezer and fresh food compartments is closed by a large outer door 5. A machinery compartment 6 in the lower portion of the refrigerator cabinet contains a refrigerant condensing unit including a compressor 7 and a condenser 8.

A single evaporator 9 is housed within an evaporator chamber 10 rearwardly from the freezer compartment 1 and above the insulating partition 3. The compressor 7, the condenser 8, suitable flow restricting means (not shown) and the evaporator are connected in closed series flow relationship to form the usual closed refrigerant circuit.

The evaporator chamber 10 is separated from the freezer compartment 1 by a vertical partition 14 forming the front wall of the evaporator chamber and the rear wall of the freezer compartment, which compartments are maintained at their desired operating temperatures by circulating air from these two compartments through the evaporator chamber and returning cooled air to the respective compartments.

More specifically, the evaporator chamber includes a first air inlet 15 in the lower portion of the partition 14 for conducting freezer air into the bottom end of the chamber 10 and an inlet 16 in the rear portion of the partition 3 connecting the fresh food compartment 2 with the lower end portion of the evaporator chamber 10. An air outlet 17 in the upper portion of the partition 14, that is above the evaporator 9, and fan means 18 associated with this outlet provides means for the forced circulation of air from the two compartments through the evaporator chamber 10. More specifically, when the fan 18 is operating air is withdrawn from the two compartments through the inlets 15 and 16 and all of the air cooled by evaporator 9 is discharged through outlet 17 into the freezer compartment. Most of this air recirculates to the evaporator chamber 10 through the inlet 15. For maintaining the desired refrigerating temperatures in the fresh food compartment 2 there is provided an air passage 20 in the forward portion of the insulating partition 1 whereby a small portion of the refrigerated air circulating through the freezer compartment 1 is conducted downwardly into the fresh food compartment 2. This passage 20, in the illustrated embodiment of the invention, comprises a slot in the forward edge of the insulating partition 3 and the walls of the slot in cooperation with the lower edge of the freezer door 4 define the interconnecting passageway. A manually adjustable damper 21 associated with the passage provides means for controlling the amount of air flow from the freezer compartment 1 to the fresh food compartment 2. Additional components of the illustrated refrigerator cabinet includes a wire rack 22 for supporting the contents of the freezer compartment 1 in spaced relationship with the upper surface of the partition 3 so as to provide for the free or unobstructed passage of the air from the freezer compartment to the chamber inlet 15. Also, for the purpose of periodically removing frost collecting on the surfaces of the evaporator 9 there is provided the defrost heater 24, preferably of the radiant heat type, supported below the evaporator 9.

The operation of the refrigeration system is controlled by a control means 26 including a temperature sensing element 27 positioned within the fresh food compartment 2. When the temperature sensed by the temperature sensing element 27 reach a predetermined maximum of for example 40 F., the compressor 7 is energized whereby condensed refrigerant is supplied to the evaporator 9. At the same time operation of the fan 18 is initiated so as to provide circulation of air from the two compartments over the evaporator 9. When the temperature sensing means 27 senses a predetermined lower temperature as for example 35 F., both the compressor 7 and the fan 18 are de-energized.

Since the refrigerating means is controlled by the sensing element 27 responsive to fresh food compartment air temperature, the compressor 7 and the fan 18 are energized whenever the temperature sensed by the sensing element 27 reaches a predetermined maximum and are deenergized when this temperature reaches a predetermined minimum. To prevent long on" and off cycles which could materially affect the temperature maintained in the freezer compartment 1, means are also provided for shortening the on and off cycles. To this end there is provided a relatively small orifice 30 in the partition 3 for conducting air from the freezer compartment 1 to a point adjacent the element 27 whenever the fan 18 is operating. More specifically when the fan 18 is operating, a small amount of cold air passes through the orifice 30 whereby the element 27 is subjected to the temperature of a mixture of this small amount of freezer air and fresh food air. This biasing effect of the freezer air causes the con trol element 27 to sense a temperature that is actually lower than the temperature of the air within the fresh food compartment 2 and thereby shortens the on cycle. When the fan 18 is stopped so that there is no freezer air flowing through the orifice 30, the sensing element 27 is subjected only to the fresh food compartment air temperature and quickly reaches the temperature at which the compressor and fan are again energized.

The energization of the defrost heater 24 for the purpose of initiating and terminating the defrost cycle may be accomplished by any of a number of known means. For example, the control circuitry for the refrigerator may include a timer adapted to initiate a defrost cycle every eight hours of compressor running time and to terminate the defrost cycle after a predetermined period sufficient to remove all of the frost which may have accumulated on the evaporator 9. During the defrosting of the evaporator 9, the defrost water collects in the bottom of the chamber 10 and flows through the passageway 16 into the fresh food compartment from which it passes through a drain hole 33 into a defrost water evaporator pan 34 in heat exchange relationship with the colldenser 8.

From the above description, it will be seen that there has been provided an automatic defrost two compartment, single evaporator refrigerator characterized by an air flow system which features a minimum ducting for conveying the refrigerated air from the evaporator to the two compartments. While there has been shown a d described a specific embodiment of the invention, it will be understood that it is not limited thereto and is intended by the appended claims cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A refrigerator comprising:

an upper freezer compartment, lower fresh food compartment and an insulating partition separating said compartments;

an evaporator chamber above said partition and rearwardly from said freezer compartment and containing an evaporator, said chamber being separate from said compartments and having an air outlet communicating with said freezer compartment,

forced air circulating means including a fan for circulating air withdrawn from both of said compartments through said chamber in heat exchange with said evaporator and discharging all of the air cooled by said evaporator through said outlet and into said freezer compartment;

said partition including an air passage connecting said freezer compartment and said fresh food compartment for conducting a portion of the air discharged into said freezer compartment to said fresh food compartment;

a conduit in said partition between said fresh food compartment and said chamber for conducting air from said fresh food compartment to said chamber and for conducting defrost water from said chamber to said fresh food compartment.

2. A refrigerator including insulated walls defining a storage volume having an access opening at the front thereof,

an outer door for closing said access opening,

a horizontal insulating partition dividing said volume into an upper freezer compartment having an access opening at the front thereof and a lower fresh food compartment,

a door for closing said access opening to said freezer compartment,

an evaporator chamber above said horizontal partition and rearwardly from said freezer compartment and separated therefrom by a vertical partition forming the front wall of said chamber and the rear wall of said freezer compartment,

an evaporator in said chamber,

said chamber including an air outlet in the upper portion of said vertical partition above said evaporator, a first inlet passage adjacent the lower edge of said vertical partition below said evaporator, and a second air inlet extending through said horizontal partition and connecting said fresh food compartment to said chamber,

air circulating means including a fan adjacent said air outlet for circulating air withdrawn from both of said compartments through said air inlets over said evaporator and discharging all of the air cooled by said evaporator into said freezer compartment through said outlet,

said horizontal partition including a passageway adja cent the front edge portion thereof for conducting a portion of the cooled air discharged into the freezer compartment into the frost portion of said fresh food compartment,

condensing means for supplying condensed refrigerant to said evaporator,

and control means for controlling the operation of said condensing means and said fan including a temperature responsive element positioned in said fresh food compartment adjacent said horizontal partition and a control orifice in said horizontal partition for conveying a relatively small portion of the air from said freezer compartment into said fresh food compartment at a point adjacent said element when said fan is operating whereby said element senses the temperature of a mixture of fresh food and freezer compartment air when said fan is operating and senses the temperature of the air in said fresh food compartment when said fan is not operating.

3. The refrigerator of claim 2 wherein said orifice is positioned in said horizontal partition at a point between and spaced from said passageway and said first inlet.

4. The refrigerator of claim 2 containing means for supporting the contents of said freezer compartment in spaced relationship with the bottom wall of said compartment and above said first air inlet to define a passageway for air flowing from the front portion of said compartment to said first air inlet.

References Cited UNITED STATES PATENTS 10 MEYER PERLIN, Primary Examiner. 

